Wing



W 9 I I E? A $TALKER 2,406,922

I v WING Filed Jan. 9, 1942 v INVENTOR- Patented Sept. 3, 1946 UNITED STATES PATENT OFFICE WING Edward A. Stalker, Ann Arbor, Mich.

Application January 9, 1942, Serial No. 426,099

8 Claims.

My invention relates to Wings equipped for boundary layer control and it has for its main object to provide a means of increasing the maximum lift coefficient for a low expenditure of power. Other objects will appear from the description and drawing.

I attain the above objects by the means illustrated in the accompanying drawing in which Figure 1 is a plan view of the aircraft;

Figure 2 is a fragmentary plan view of the wing; l

Figure 3 is a section along the line 33 in Fi ure 1; and

Figure 4 is the same section as Figure 3 with th flaps depressed.

I have discovered that a great increase in the lift of a wing equipped with a suction slot can be achieved if a second slot is properly located with respect to the forward slot or slots.

It is well known that if the boundary layer on a Wing is inducted into the wing there is a great increase in the maximum lift coefficient of the wing. It has been found however that on thin wings a great suction is required to achieve rather mediocre results. That is a great amount of power and high suction must be employed. Furthermore the published experiments on this subject indicate that the best location for the slot is near the point on the wing chord 52 per cent of the chord back from the wing nose.

I have discovered that a larg gain can be achieved by eliminating a source of trouble which has not before been recognized. I have found thatif a large suction is employed near the middle of the wing the maximum lift coefilcient does. increase but at a slow rate beyond a certain value becaus this high suction causes a reverse flow between the suction slot and the trailing edge of the wing. That is, there occurred a forward flow from the trailing edge toward the slot. This caused the main rearward flow to leave the wing a short distance back f the suction slot. This effect is particularly marked with thin wings which have such a small radius of curvature at their nose that a high suction is necessary at the suction slot.

I have found a remedy for the above defect which has resulted in large gains in maximum lift coefficient for a given powerexpenditure of thepump or blower. This consists in locating a suction slot as near the trailing edge as is structurally practicable and exerting a sufficient suction through it to counteract the forward slot whose suction tends to pull air forward from the trailing edge. A slot at the trailing edge is alone 2 ineffective on a thin wing in increasing the lift significantly, yet when it is combined with a forwardly located s'lot it exerts a very great beneficial influence.

Turning now to the figures, the wing is I com prised of the main body 2 and the flaps 3 and 4 which are rotatable about the hinges 5 and 6 respectively.

The first flap 3 has the induction slot 1 in communication with the wing interior while the flap 4 has the induction slot 8 located very close to the trailing edge of the wing.

Th blower 9 inducts the boundary layer through the slots 1 and 8 and the suction at the rear slot serves to restrain a forward flow induced by the front slot.

An important feature of the Wing is the provisionof a highly arched mean camber line accompanied by an upper chordwise contour of large radius of curvature. The value of this radius should exceed substantially the thickness of the wing at the juncture of the wing main body and th flap.

The flaps are given an unusual arching so that in the retracted position the .top of the wing section has a scalloped appearance but when the naps are depressed the upper arches register to provide an upper camber of generous radius of curvature. The flap adjacent th main body has a smaller radius of curvature for its upper camber than that of the upper camber of the rear part of the main body. The main body of course terminates with some radius at its end so the portion of the upper camber referred to is taken ahead of the rear 10 per cent of the main body and aft of its mid point.

A tangent II to the wing across the concavity formed between the upper extradoses touches this surface a substantial distance ahead of the bottom of the concavity as at 10. See Figure 3. This assures a gradual descent of the contour to the bottom of the concavity for the purpose of eliminating turbulenc and drag. Preferably the point of tangency in of the tangent II should lie ahead of the bottom of the concavity a distance greater than twice the depth of the concavity.

I use the term lift flap in the claims to refer to the type which are depressed coincidentally on opposite sides of the aircraft for increasing the total lift, in contradistinction to aileron flaps which ar operated differentially.

While I have described a specific form of the invention it is to be understood that I do not intend to limit myself to precisely this but intend to claim my invention broadly as indicated in the appended claims.

I claim:

1. An aircraft wing of the character described which comprises a wing main body, a flap, means for adjustably supporting said flap from said wing main body providing for movement thereof from an upper raised position to a lowered position effecting an increase in the mean camber height of the wing, means forming a forward induction slot in the upper camber surface of the wing at a point intermediate the leading and trailing edges of the wing, means forming another induction slot in predetermined spaced relation with respect to said forward slot and located substantially along the trailing edge of said flap, and power operated means withinsaid wing for inducing a flow of air through both said slots with the induction through said rearward slot restraining the tendency to cause forward flow of the air on the trailing portion of said wing as a result of said forward slot.

2. An aircraft wing of the character described which comprises a relatively thin wing main body, a flap tapering substantially to a line at its trailing edge, means for adjustably supporting said flap from said wing main body providing for movement thereof from an upper raised position to a lowered position effecting an increase in the mean camber height of the wing, means forming a forward induction slot in the upper camber surface of the wing at a point intermediate the leading and trailing edges of the wing, mean forming another induction slot inpredetermined spaced relation with respect to said forward slot and located substantially along the trailing edge of said flap on the upper surface thereof, and power operated means within said wing for inducing a flow of air through both said slots with the induction through said rearward slot restraining thetendency to cause forward flow of the air on the trailing portion of said wing as a result of said forward slot.

3. An aircraft wing of the character described which comprises a relatively thin wing main body, a flap, means for adjustably supporting saidfiap from said wing main body providing for movement thereof from an upper raised position to a lowered position effecting an increase in the mean camber height of the wing to a value greater than 12% of the wing chord length, means forming a forward induction slot in the upper camber surface of the wing at a point aft of the mid point and forwardly of the trailing end thereof, means forming another induction slot in predetermined spaced relation with respect to said forward slot and located substantially along the trailing edge of said flap, and power operated means within said wing for inducing a flow of air through both said slots with the induction through said rearward slot restraining thetendency to cause forward flow of the air on the trailing portion of said wing as a result of said forward slot.

4. An aircraft wing of the character described which comprises a wing main body, the radius of curvature of the rearward portion of the upper camber surface of said wing main body being substantially in excess of the thickness of the adjacent portion of the wing, a flap, means for adjustably supporting said flap at the end of said wing main body providing for movement thereof from an upper raised position to a lowered position effecting an increase in the mean camber height of the wing, means forming a forward 4 induction slot in the upper camber surface of the wing at a point intermediate the leading and trailing edges thereof, means forming another induction slot substantially along the trailing edge of said flap, and means within said wing for inducing a flow of air through both said slots with the induction through said rearward slot restraining the tendency to cause forward flow of the air on the trailing portion of the wing induced by said forward slot.

5. An aircraft wing of the character described which comprises a wing main body, the radius of curvature of the rearward portion of the upper camber surface of said wing main body being substantially in excess of the thickness of the adjacentportion of the wing, a flap having a smaller radius of curvature for its upper camber surface than that of the upper camber surface of said rearward portion of the wing main body, means for adjustably supporting said flap at the end of said wing main body providing for movement thereof from an upper raised position to a lowered position effecting an increase in the mean camber height of the wing, means forming a forward induction slot in the upper camber surface of the wing at a point intermediate the leading and trailing edges thereof, means forming another induction slot substantially along the trailing edge of said flap, and means within said wing for inducing a flow of air through both said slots with the induction through said rearward slot restraining the tendency to cause forward flow of the air on the trailing portion of the wing induced by said forward slot.

6. An aircraft wing of the character described which comprises a wing main body, the radius of curvature of the rearward portion of the upper camber surface of said wing main body being substantially in excess of the thickness of the adjacent portion of the wing, a flap, means for adjustably supporting said flap at the end of said wing main body providing for movement thereof from an upper raised position to a lowered position effecting an increase in the mean camber height of the wing, the upper surface of said flap being arched to produce with said wing main body in the raised position of said flap a scalloped upper surface, the upper surfaces of said wing main body and of said flap registering in the lowered position thereof to provide a continuous upper camber surface of a radius of curvature substantially in excess of the wing thickness, means forming a forward induction slot in the upper camber surface of the wing at a point intermediate the leading and trailing edges of the wing, means forming a rearward induction slot substantially along the trailing edge of said flap, and means within said wing for inducing a flow of air through both said slots with the induction through said rearward slot restraining the tendency to cause forward flow of the air on the trailing portion of the wing induced by said forward slot.

7. An aircraft wing of the character described which comprises a relatively thin wing main body, the radius of curvature of the rearward portion of the upper camber surface thereof being substantially in excess of the thickness of the adjacent wing, a plurality of flaps, means for adjustably supporting said flaps in tandem relation at the trailing edge of the wing main body providing for movement thereof from an upper raised position to a lowered position effecting an increase in the mean camber height of the wing, means forming a forward induction slot in the upper camber surface of the wing at a point intermediate the leading and trailing edges of the wing, means forming a rearward induction slot substantially along the trailing edge of the rearmost flap, and means within said wing for inducing a flow of air through both said slots with the induction through said rearward slot restraining the tendency to cause forward flow of the air on the trailing portion of the wing induced by said forward slot.

8. An aircraft wing of the character described which comprises a relatively thin wing main body, the radius of curvature of the rearward portion of the upper camber surface thereof being substantially in excess of the thickness of the adjacent wing, a plurality of flaps, means for 6 adjustably supporting said flaps in tandem relation at the trailing edge of the wing main body providing for movement thereof from an upper raised position to a lowered position effecting an increase in the mean camber height of the wing, means forming a forward induction slot in the upper camber surface of a forward flap, means 7 forming a rearward induction slot substantially along the trailing edge of the rearmost flap, and means within said wing for inducing a flow of air through both said slots with the induction through said rearward slot restraining the tendency to cause forward flow of the on the trailing portion of the wing induced by said forward slot.

EDWARD A-. STALKER. 

